Guardianship gives you authority to make decisions for your loved one, even after he or she becomes a legal adult.

Everyone aged eighteen and older is an adult in the eyes of the law. The law takes no account of disabilities. Once your special needs child turns eighteen, he or she is legally an adult.
What does this mean? Until your child turns eighteen, you are in the driver’s seat. You have access to all your child’s educational and medical records. You make medical, legal, and financial decisions for your child.
All this changes once your child turns eighteen. At that point, he or she is legally an adult. You no longer have the automatic right to see your child’s medical or financial records. Medical, legal, and financial decisions become your child’s responsibility, not yours. Your child can sign a contract; you cannot sign one for him or her. Your child’s disability makes no difference in the eyes of the law.

What if your loved one is not capable of making his or her own decisions?

This is what guardianship is for. If a person is not capable of making decisions for himself or herself, a court may appoint a guardian to take those responsibilities for him or her. Parents can petition for guardianship either before or after their child turns eighteen.
Guardianship is a legal proceeding that results in the court issuing an order of guardianship. This order states who is the guardian or guardians for that person, and what authority the guardian or guardians have.
By petitioning for guardianship, you ensure that you, or another trusted individual or institution, can continue to care for your loved one. Guardianship has a certain amount of flexibility. You can name one or more people as joint guardians. You can also name a successor guardian, for when you (and any other initial guardians) are no longer available to act. The successor guardian can be one or more individuals, or it can be an institution. It’s up to you.